Fabricating a contact rhodium structure by electroplating and electroplating composition

Abstract

A contact rhodium structure is fabricated by a process that comprises obtaining a substrate having a dielectric layer thereon, wherein the dielectric layer has cavities therein into which the contact rhodium is to be deposited; depositing a seed layer in the cavities and on the dielectric layer; and depositing the rhodium by electroplating from a bath comprising a rhodium salt; an acid and a stress reducer; and then optionally annealing the structure.

1. A process for fabricating a contact rhodium structure which comprises obtaining a substrate having a dielectric layer thereon, wherein the dielectric layer has cavities therein into which the contact rhodium is to be deposited;
 depositing a seed layer in the cavities and on the top surface of the dielectric layer outside of the cavities; and depositing the rhodium by electroplating from a bath comprising a rhodium salt; an acid and a stress reducer, wherein the stress reducer is at least one member selected from the group consisting of a halide, a complex of rhodium sulfate having bridged bidentate sufphato groups, a sulfamic acid, a sulfonic acid, a combination of an aluminum ion a dicarboxylic or polycarboxylic acid, and an alcohol; and then annealing the structure, 
 wherein the electroplating comprises an initial current density of about 0.1 milliamps/cm 2  to about 5 milliamps/cm 2  for about 1 to about 20 seconds followed by a ramping up of the current density in about 5 to about 120 seconds and a higher current density of about 1 to about 100 milliamps/cm 2  for about 60 seconds to about 60 minutes plate to the desired thickness. 
 
     
     
       2. The process of  claim 1  which further includes depositing an adhesion layer between the seed layer and dielectric layer. 
     
     
       3. The process of  claim 2  wherein said adhesion layer is at least one member selected from the group consisting of titanium, tantalum, titanium nitride and tantalum nitride. 
     
     
       4. The process of  claim 3  wherein the adhesion layer is about 20 angstroms to about 200 angstroms thick. 
     
     
       5. The process of  claim 1  wherein the seed layer is at least one member selected from the group consisting of ruthenium, platinum, copper, tungsten, cobalt, sulfide and silicon. 
     
     
       6. The process of  claim 1  wherein the seed layer is ruthenium. 
     
     
       7. The process of  claim 1  wherein the seed layer is about 0.006 μm to about 0.25 μm thick. 
     
     
       8. The process of  claim 1  wherein the cavities have an aspect ratio of about between 2 and about 20. 
     
     
       9. The process of  claim 1  wherein the cavities have an aspect ratio of between about 4 and about 10. 
     
     
       10. The process of  claim 1  wherein the cavities have a CD dimension down to about 40 nanometers. 
     
     
       11. The process of  claim 1  wherein the rhodium salt is at least one member selected from the group consisting of rhodium sulfate, rhodium phosphate and rhodium chloride. 
     
     
       12. The process of  claim 1  wherein the rhodium salt is rhodium sulfate. 
     
     
       13. The process of  claim 1  wherein the amount of rhodium salt in the bath is about 1 to about 100 grams/liter. 
     
     
       14. The process of  claim 1  wherein the amount of rhodium salt in the bath is about 1 to about 10 grams/liters with a specific example being 5 grams/liter. 
     
     
       15. The process of  claim 1  wherein the acid is at least one member selected from the group consisting of sulfuric acid, hydrochloric acid and phosphoric acid. 
     
     
       16. The process of  claim 1  wherein the acid is sulfuric acid. 
     
     
       17. The process of  claim 1  wherein the bath has a pH of about 0.1 to about 3. 
     
     
       18. The process of  claim 1  wherein the bath has a pH of about 0.5 to about 1. 
     
     
       19. The process of  claim 1  wherein the rhodium has a resistivity between about 5 micro-ohm-cm to about 50 micro-ohm-cm and between about 5 micro-ohm-cm to about 20 micro-ohm-cm when annealed above 190° C. 
     
     
       20. The process of  claim 1  wherein the electroplating is carried out at temperatures of about 10° C. to about 80° C. 
     
     
       21. The process of  claim 1  wherein the substrate is at least 200 mm. 
     
     
       22. The process of  claim 1  wherein a porous shield is present between anode and the substrate being plated. 
     
     
       23. The process of  claim 22  wherein the porous shield has a porosity that increases from the edge of the substrate inwards towards the center. 
     
     
       24. The process of  claim 1  wherein the structure is annealed at temperatures above 190° C. and in an air, O 2 , N 2 , H 2 , forming gas, argon or helium atmosphere. 
     
     
       25. The process of  claim 1  which further comprises planarizing the structure. 
     
     
       26. A structure obtained by the process of  claim 1 . 
     
     
       27. The structure of  claim 26  wherein the cavities have an aspect ratio of at least about 2. 
     
     
       28. A process for fabricating a contact rhodium structure which comprises obtaining a substrate having a dielectric layer thereon, wherein the dielectric layer has cavities therein into which the contact rhodium is to be deposited;
 depositing a seed layer in the cavities and on the top surface of the dielectric layer outside of the cavities; and depositing the rhodium by electroplating from a bath comprising a rhodium salt; an acid and a stress reducer, wherein the stress reducer is at least one member selected from the group consisting of a halide, a complex of rhodium sulfate having bridged bidentate sufphato groups, a sulfamic acid, a sulfonic acid, a combination of an aluminum ion a dicarboxylic or polycarboxylic acid, and an alcohol; and then annealing the structure, 
 wherein the cavities have an aspect ratio of between about 2 and about 20, and 
 wherein the electroplating comprises an initial current density of about 0.1 milliamps/cm 2  to about 5 milliamps/cm 2  for about 1 to about 20 seconds followed by a ramping up of the current density in about 5 to about 120 seconds and a higher current density of about 1 to about 100 milliamps/cm 2  for about 60 seconds to about 60 minutes plate to the desired thickness. 
 
     
     
       29. The process of  claim 1  wherein the cavities have a CD dimension about 30 to about 240 nanometers. 
     
     
       30. The process of  claim 1  wherein the cavities have a CD dimension about 40 to about 100 nanometers. 
     
     
       31. The process of  claim 1  wherein the substrate is at least about 200 mm. 
     
     
       32. The process of  claim 1  wherein the bath has a pH of about 0.1 to about 3 and wherein the electroplating is carried out at temperatures of about 10° C. to about 80° C. 
     
     
       33. The process of  claim 32  wherein the bath has a pH of about 0.5 to about 1. 
     
     
       34. The process of  claim 28  wherein the bath has a pH of about 0.1 to about 3 and wherein the electroplating is carried out at temperatures of about 10° C. to about 80° C. 
     
     
       35. The process of  claim 34  wherein the bath has a pH of about 0.5 to about 1.